1. Field of the Invention
The present invention is related to a display apparatus including an integrated body of an optical waveguide and a driving method thereof.
2. Description of the Related Art
Currently, as a widely used display apparatus, there are, for example, CRTs (Cathode Ray Tubes), LCDs (Liquid Crystal Displays), PDPs (Plasma Display Panels), OLEDs (Organic Light Emitting Displays) and FEDs (Field Emission Displays). As for CRT, since depth is required in size due to carrying out electronic line scanning, currently, LCD, PDP, OLED and FED etc., which are referred to as FPDs (Flat Panel Displays), are becoming mainstream. Each FPD performs light modulations utilizing light emitting mechanisms or light valves etc. for each two-dimensionally arranged pixel. In order to transmit analogue information regarding this light modulation to each pixel, FPD is configured to take advantage of a matrix structure which has high accuracy. Accordingly, when preparing the FPD, techniques such as carrying out film forming by vacuum processes, such as a spatter method, which uses, for example, a large area substrate such as a glass substrate, or a highly accurate shape formation technique represented in photo-etching processes are adapted.
Meanwhile, a method which does not carry out light modulation on each pixel positioned at the intersection point of matrix wiring is also being considered. In this method, light modulation etc. are carried out on portions other than the pixel portions. Light is emitted after being guided to a desired position. This configuration allows light which is incident from a light source upon an optical waveguide so as to satisfy total reflection conditions to have its light emitting position defined at a position in a part of the optical waveguide by, for example, displacement of a light output element. Further, according to this method, the role of each pixel portion can be reduced to guiding light adjusted to a desired strength and selecting light output.
For example, JP-A 1-185692 (KOKAI) suggests a method which, instead of providing a light source and a light modulating element such as a light valve to each pixel, carries out light modulation by using a strength modulator attached to a light source. After the light is guided to a desired pixel position, it is emitted at the pixel position. In other words, after the light whose strength is adjusted at the light source is transmitted to a desired position by light guiding under total reflection conditions of a core and clad, which are optical waveguides, refractivity of a core material at such position is changed, and light is emitted. By changing the refractivity of the core material partially by applying electric field, it becomes an area which does not satisfy total reflection conditions in the core and clad. Therefore, in an area which does not satisfy total reflection condition, the guided light is emitted from a core which is an optical waveguide.
However, a scanning driving method for display action is required in a display apparatus having a structure integrated by a plurality of one-dimensional optical waveguides such as optical fibers. In the above mentioned display apparatus structure, scanning applies electric field to an optical waveguide and changes reflectivity to determine a scanning position. In order to maintain favorable display performance, a changing of refractivity at the correct time is required.
Further, since the scanning determines the scanning position by selecting contact or noncontact with the optical waveguide, when not in contact, a spacer should define a noncontact state between the optical waveguide and the scanning line. Therefore, since it is necessary to control space between the optical waveguide and each signal line strictly in accordance with a displaceable amount upon selecting the scanning line, strict control in production, such as controlling the height of the spacer for structure formation, is required.